1. Field of the Invention
This invention relates to a camera having a zoom lens and capable of trimming photographing.
2. Related Background Art
A camera capable of trimming photographing is known which sets a trimming magnification at the time of photographing. The photographed picture is trimmed at its top, bottom, left and right sides in accordance with the set trimming magnification at the time of printing. A photograph can thereby be obtained which is equivalent to a photograph taken by zoom-up photographing at a magnification greater than the magnification determined by the maximum focal length of the zoom lens. (For example, a camera of this type is disclosed in Japanese Patent Laid-Open Application No. 61-285432).
FIG. 1 shows the relationship between a focal length F ranging from 35 to 80 mm of a zoom lens capable of trimming photographing, a trimming magnification .beta. and a pseudo focal length GF.
When a zooming switch for moving the zoom lens is operated to a zoom-up side, the zooming lens is moved from a minimum focal length FW ((F=35 mm) position (hereinafter referred to as "wide-angle end") to a maximum focal length FT (F=80 mm) position (hereinafter referred to as "telephoto end"). When the trimming magnification .beta. is 1, the pseudo focal length GF has the same value as the focal length of the zoom lens in the optical zooming range of the zoom lens (F=35 to 80 mm).
If the zoom switch is further operated to the zoom-up side when the zoom lens is at the telephoto end FT, the photography mode is changed from an ordinary mode to a trimming photographing mode, so that the pseudo focal length GF is increased with the increase in the trimming magnification .beta.. That is, as the trimming magnification .beta. is successively increased from 1 to 1.5, 2.0, and 2.5, the pseudo focal length GF is increased from 80 to 120, 160, and 200. The trimming magnification .beta. can be set in a range as determined by the maximum trimming rate of enlarging printing of the ordinary laboratory print size.
When a picture is taken in this trimming photographing mode, the trimming magnification .beta. determined at the time of photographing is recorded on a film portion in the vicinity of the picture frame. At the time of printing, the picture frame is trimmed at the top, bottom, left and right sides in accordance with the trimming magnification .beta. set at the time of photographing and is enlarged to a predetermined size by adjusting the focal length of the printing lens.
In the case of a conventional camera capable of trimming photographing, since various magnifications are set in the variable range of the trimming magnification according to different photographed subjects, it is necessary to frequently change the focal length of the printing lens during printing according to the trimming magnifications set at the time of photographing. The time required for printing is thereby increased and the printing cost is correspondingly increased.
In the case of compact cameras having a simplified photographing lens construction, the zoom lens tends to have a greater F value on the long focus side (hereinafter referred to as "telephoto side") in comparison with the short focus side (hereinafter referred to as "wide-angle side"). Therefore, if zoom-up photographing is performed at a telephoto side of the zoom lens, there is a possibility of automatic exposure (AE) control failure with respect to a low-luminance subject, and there is a problem of a reduction in the linkage distance at the time of flash photography by linkage to a strobe unit or an increase in the frequency of use of the strobe unit and, hence, a reduction in the battery life.
To prevent these problems, trimming photographing on the wide-angle side of the zoom lens may be performed to take a pseudo zoomed-up photograph, and such trimming photographing is more advantageous than taking a zoomed-up photograph on the telephoto side of the zoom lens in some cases. By trimming photographing, however, the enlargement magnification at the time of printing is increased so that the printed image is grainy. It is therefore preferable to use the zoom lens on the telephoto side as widely as possible to limit the trimming rate.
In conventional cameras capable of trimming photographing, however, the ordinary photographing range and the trimming photographing range are changed at the telephoto end of the zoom lens, and trimming photographing cannot be selected according to photographing conditions at the wide angle end.
At the time of pseudo zoom photographing, it is desirable to set an optimum photographing magnification, i.e., an optimum focal length according to photographing conditions as in the case of ordinary zoom photographing. There is therefore a need to continuously change the focal length at the time of changeover from the optical zooming range to the pseudo zooming range, and there is also a need to set a desired pseudo focal length in the pseudo zooming range as in the optical zooming range.
In conventional cameras capable of trimming photographing, however, if the pseudo focal length for pseudo zoom photographing is continuously changed, an arbitrary trimming magnification is set according to photographing conditions each time a picture is taken and it is necessary to frequently change the focal length of the printing lens during printing according to trimming magnifications set at the time of photographing. The time required for printing is thereby increased and the printing cost is correspondingly increased.
If as shown in FIG. 2 the zooming switch is operated to the zoom-down side while setting the trimming magnification .beta. to, for example 2.5, the focal length F and the pseudo focal length GF of the zoom lens are reduced, so that the pseudo focal length GF is 87.5 mm at the wide-angle end (F=35 mm) of the zoom lens. That is, in a pseudo zoom photographing mode of a trimming magnification of .beta.=2.5, a pseudo focal length GF of 87.5 to 200 mm can be obtained. Similarly, in a pseudo zoom photographing mode of a trimming magnification of .beta.=2.0, a pseudo focal length GF of 70 to 160 mm can be obtained and, in a pseudo zoom photographing mode of a trimming magnification of .beta.=1.5, a pseudo focal length GF of 52.5 to 120 mm can be obtained. That is, if a plurality of values of trimming magnification .beta. are set, the zooming range at one magnification overlaps the zooming range at another magnification. If the number of stepped values of trimming magnification .beta. are increased, each overlapping range is extended. Accordingly, a pseudo focal length GF of, for example, 120 mm can be achieved by setting the focal length F of the zoom lens to 80 mm at the telephoto end with respect to a trimming magnification .beta.=1.5, and can also be achieved by setting the focal length F of the zoom lens to 60 mm with respect to a trimming magnification .beta.=2.0 or by setting the focal length F of the zoom lens to 48 mm with respect to a trimming magnification .beta.=2.5. That is, if a plurality of values of trimming magnification .beta. are finely set within the range determined by the maximum trimming rate of enlarging printing of the ordinary laboratory print size, the same pseudo focal length GF can be obtained with respect to a plurality of trimming magnifications.
When a picture is taken in such a pseudo zoom photographing mode, the trimming magnification .beta. at the time of photographing is recorded on a film portion in the vicinity of the picture frame. At the time of printing, the picture frame is trimmed at the top, bottom, left and right sides in accordance with the trimming magnification .beta. set at the time of photographing and is enlarged to a predetermined size by adjusting the focal length of the printing lens. If the trimming magnification .beta. is increased, the enlargement magnification is also increased so that the resulting print is markedly grainy.
In conventional cameras capable of trimming photographing, however, when a desired focal length is set, the selection of one of a plurality of possible trimming magnifications with which the focal length can be set is not specified. In such an event, therefore, there is a possibility of the desired focal length being set with a greater trimming magnification even though the desired focal length can be set with a smaller trimming magnification. In this case, the enlargement magnification at the time of printing is increased so that the resulting print is poor in quality.
Various cameras having zoom lenses have been proposed, including those having a zooming type finder (hereinafter referred to as "zoom finder") whose magnification is changed according to the focal length of the photographing lens by moving a finder zooming lens along the optical axis of the zooming lens by interlocking with zooming (a change in the photographing magnification) of the photographing lens (zoom lens).
A type of camera capable of trimming photographing is also known in which information (trimming information) that only a predetermined trimmed region in an exposed region defined on a film by a shutter release is to be printed is recorded, for example, on a marginal portion of the film (as in the camera disclosed in Japanese Patent Laid-Open Application No. 61-285432. The recorded trimming information is read in the laboratory process, and only the trimmed region is enlarged and printed in accordance with this information. Since the trimmed region is smaller than the printed area of the ordinary photography, the photographing magnification is changed at the time of changeover between a trimming photographing mode and an ordinary photographing mode, and there is a need to change the finder magnification by interlocking with the mode changeover.
The camera disclosed in Japanese Patent laid-Open Application No. 61-285432 has a photographing zoom lens and a zoom finder zoomed with a zoom lens barrel. The zoom lens and the zoom finder are interlocked. More specifically, when the zoom lens barrel is further moved to the long-focus side from the telephoto end of the photographing zoom lens, an ordinary photographing mode is automatically changed into a trimming photographing mode and the zoom finder is further zoomed up while the photographing zoom lens is stopped at the same position. When the zoom lens barrel is further moved to the short-focus side from the wide-angle end, the ordinary photographing mode is automatically changed into another trimming photographing mode while the zoom lens and the zoom finder are maintained in the same position. In this manner, the magnification of the zoom finder is changed by interlocking with changeover between the trimming photographing modes and the ordinary photographing mode.
The conventional cameras capable of trimming photographing are designed to zoom a zoom finder through the whole range of zooming in ordinary and trimming photographing modes, and therefore require a zoom finder having a high zooming ratio and, hence, a large zoom finder unit.
To limit the size of the finder unit, a method may be adopted in which a converter lens is inserted in a trimming photographing mode or ordinary photographing mode or two converter lenses are interchanged at the time of mode changeover, so that the finder magnification is changed separately of zooming of the zoom finder. However, it is disadvantageous in terms of economy to separately provide a drive source for zooming the zoom finder and another drive source for inserting (interchanging) the converter lens, and there is also a possibility of an increase in the overall size of the finder unit including the zoom finder and the converter lens.